How can i fix this render issue?
You have bad topology: essenciatlly non-manifold vertices and duplicated vertices.
It is noticeable in frame 32. If you disable the modifiers, change to solid mode, you will see the strange artifacts on the surface. I tried to dissolve the non-manifold vertexes and to remove double vertexes, then recalculate the normals, and problem is only slightly fixed. On my advise, the fastest way to fix, will be with retopology: you have to remake the head, but this time, you have to try to keep a simple geometry. Try to see some tutorials on how to do retopology faster. If you are in a hurry, and don't have time to do it correctly, you can cheat it by: while in edit mode > press T to open left menu, go to "shading/Uv's" tab> on shading the faces, select flat> press N to open the right menu > press A once or twice to select all the object> on the N menu, under Tranform tab, on edges data, decrease the "mean crease" to 0, and try a render (worked for me). Yet, if I were you, I would consider retopology in the future. Good luck.